What are ramifications if 230V 50Hz motor is connected to step-up transformer from 115V 60Hz input?

All any motor cares about is a volt per hertz ratio. That being said, I am assuming you are stepping up 115 vac to 230 volt vac. The motor is going to run faster at 60 hertz than at 50 hertz. If the motor was rated for 1,500 rpm at 50 hertz, it will now rum 1,800 rpm. Depending on the application, you could very easily overload the motor because the Hp requirement at 1,500 rpm is very different than the HP requirement at 1,800 rpm. This is especially true for pumps and fans. You will need to change pulleys to keep the gearing thesame.